The thickness of some parts of one of the horses on St. Mark's Basilica (Venice), Marcus Aurelius' horse in the Piazza del Campidoglio (Rome), the Colossus of Barletta, and a statue of Dionysus dating from the times of the Roman Empire has been measured by ultrasonics. By analyzing and comparing the results, it has been possible to establish an auxiliary method for studying how the statues were made, and check the consistency, compactness and thickness of zones subjected to bending and compressive stresses in statues exhibiting cracks, mechanical damage and casting defects. -- AATA